It is important for the production of reliable and efficacious semiconductor wafers that they be kept free from particles and organic film depositions that may adhere to the wafers during fabrication or storage. Indeed, reducing particles or defects on semiconductor wafers is one of the major issues involved in producing high-yield integrated-circuit devices. A semiconductor wafer is typically fabricated from silicon with various materials implanted or applied on its surface. Airborne contaminants may adhere to this surface, or contaminants may become deposited on the surface from other sources during or after wafer fabrication, such as from the wafer holder, chemical solutions, storage boxes, machines, other wafers, or the like. Even deionized water used in a rinsing step may introduce particles that adhere to the wafer surface. As wafers become smaller, even very small particles may adhere to the wafer, decreasing the yield and product reliability. Despite the significance of this problem, present industry knowledge and technology have been unable to fully address or eliminate it and instead, numerous pre- and post-fabrication cleaning processes have been invoked.
To illustrate, under prior art methods, the particle contaminants have been addressed through use of a multitude of cleaning or wafer-protection techniques, such as chemical pre-cleaning methods; strict control over the wafer environment during fabrication and storage; and/or through post-fabrication rinsing or cleaning processes. Known approaches for controlling particle deposition include a wafer scrubbing and pre-cleaning combination, referred to as RCA-type cleaning (typically NH.sub.4 OH+H.sub.2 O.sub.2, then HCl+H.sub.2 O, followed by de-ionized water rinse), with or without ultrasonic or megasonic functions, and/or use of mini-environments such as standard mechanical interface (SMIF) containers designed to control the wafer environment. Many cleaning processes have been used, including wet-chemical, vapor dry etching, and electron flux irradiation techniques.
The instant invention has advantages in that it provides a method of reducing semiconductor wafer sensitivity to contaminants, thus avoiding or reducing the need to depend upon chemical pre-cleaning or wafer scrubbing applications. Further advantages may appear more fully upon consideration of the description below.